The breeding parameters and the egg and nestling morphology of Cyanistes caeruleus populations from rural, intermediate, and urban sites in Algeria and the relationships of those variables with lead contamination were studied during three consecutive years. Breeding success was explained only by predation and vandalism rates. Predation was higher in the rural area, whereas vandalism was higher in the urban site. The other measured breeding parameters and egg characteristics were relatively insensitive to study site. The morphology of urban nestlings exhibited a trend toward smaller body size and mass compared to individuals from intermediate and rural sites. Although lead concentrations were higher in the tissues of urban birds than in intermediate and rural individuals, we did not detect a clear influence of this variable on nestling morphology. We conclude that urbanization influenced blue tit breeding parameters through predation and vandalism and nestling morphology through mechanisms other than lead pollution.

Highlights:

► Life history traits in relation to lead contamination were studied in blue tits from rural, industrial and urban sites.

► The study took place in Annaba, the fourth most populated city of Algeria, during 3 consecutive years.

► Breeding success depended on predation and vandalism, which were high in the rural and urban sites, respectively.

► Urban nestlings exhibited a trend toward smaller body size and mass, which was not explained by lead contamination.

► Urbanization influences breeding success and nestling morphology in blue tits through other mechanisms than lead pollution.